What does it mean?
B1386 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Power Tailgate Sensor Pulse A Circuit Malfunction .
Symptoms
- The tailgate stops part way, reverses for no reason, or closes at full speed because the module cannot see its position
- False obstacle detection during opening or closing
- Power operation shuts down after several failed attempts and the gate must be moved by hand
- Chime or a warning message about the power tailgate
- The learned open position is lost, so the gate no longer stops where it used to
Likely causes
- Broken or chafed conductor in the pulse A wire inside the tailgate hinge boot
- Water in the drive unit or pulse sensor connector after a tailgate seal leak
- Failed hall element inside the drive unit or strut motor
- Loss of the 5 volt reference or the ground shared by the pulse sensor
- Corroded connector at the tailgate drive unit
- Worn drive gearbox producing erratic or missing pulses
- Module input fault
How to fix it
- Compare pulse A with pulse B on the scan tool while moving the tailgate slowly, since the good channel is the reference for the faulty one
- Check the 5 volt supply and the ground at the drive unit connector before condemning the sensor
- Inspect the drive connector for water and corrosion, and dry the area if it is wet
- Flex the hinge boot harness while watching the pulse count for dropouts
- On vehicles with a drive unit on each side, compare the two to confirm which one has failed
- Repair the damaged wire or replace the drive unit when the sensor is proven at fault
- Run the travel relearn procedure after the repair and check that the gate stops correctly at both ends